Why do people keep laughing at me?

Today my cousin and I went out to the mall to do some shopping.
I wanted to dress nice and look good in case there were some babes walking around. I threw on a brown polo, a pair of jeans and my favorite trapper hat that I just bought a few weeks back and I was thinking to myself " I'm looking freaking hot ! " When we got to the mall we went into this store where we were greeted by the store employee's " one was a dude, and the other a betty "
The guy said " Hey there chicks... whoops I'm sorry" and continued laughing at me along with the girl. I walked on and shrugged it off of course.
We left that store and went into another and were also greeted by the employees. When we got in the store there was this guy who had turned around and looked at me with a dumbfounded look upon his face and would not stop staring at me. Acting tough I told him to " back the f**k up " and walked on and little did I know the joke was on me, literally.

Now on the way out of the mall we had been confronted by the same guy who we had seen in the second store. He stood there, watching and laughing along with his friends an their girl friends.
I started telling myself that they thought my hat was funny or weird so I shurgged it off.

" Fast Forward to next morning " it is now 6 am I just got back from getting breakfast and going to the store. A few people laughed at me and I started getting mad. I come home and realize that on the front of my brown polo was a huge cum stain. I don't know If i'll ever show my face back at that praticualr mall ever again because there are no words to describe how embarrassed I was and am.